Bosch cordless drill battteries
 

Anyone any suggestions for getting longer life out of NiCd drill batteries.
Mine always seem to expire after a couple of years or is this normal life? I
only use the drill every couple of weeks for perhaps 10 minutes work and
only recharge when its completely flat. When I've opened up a battery pack,
I usually find one or 2 of the 10 cells is really low on voltage, the
others being on about 1.2volts.

Geoff.

Bosch cordless drill battteries
 

In article ,
Geoff Norfolk wrote:
Anyone any suggestions for getting longer life out of NiCd drill
batteries. Mine always seem to expire after a couple of years or is this
normal life? I only use the drill every couple of weeks for perhaps 10
minutes work and only recharge when its completely flat. When I've
opened up a battery pack, I usually find one or 2 of the 10 cells is
really low on voltage, the others being on about 1.2volts.

Sounds like typical cheap Ni-Cads. And probably a nasty charger. But don't
run the batteries totally flat - the 'memory' thing is a con. Recharge
after there is a drop off in performance. Quality Ni-Cads with a sensible
charger should have a life of about 5 years with this sort of use.

--
*Laugh alone and the world thinks you're an idiot.

Dave Plowman London SW
To e-mail, change noise into sound.

Bosch cordless drill battteries
 

On Thu, 27 Oct 2005 17:48:44 GMT, "Geoff Norfolk" wrote:

Anyone any suggestions for getting longer life out of NiCd drill batteries.
Mine always seem to expire after a couple of years or is this normal life? I
only use the drill every couple of weeks for perhaps 10 minutes work and
only recharge when its completely flat. When I've opened up a battery pack,
I usually find one or 2 of the 10 cells is really low on voltage, the
others being on about 1.2volts.

Geoff.

If a cell reads zero volts, it has probably dendrited - whiskers of metal form and short the cell.
These can often be recovered by passing a very brief, heavy current (10-30 amps for a C-size cell
for a second or 2 max) through it.

Bosch cordless drill battteries
 

Geoff Norfolk wrote :
Anyone any suggestions for getting longer life out of NiCd drill batteries.
Mine always seem to expire after a couple of years or is this normal life? I
only use the drill every couple of weeks for perhaps 10 minutes work and
only recharge when its completely flat.

Which will cause some cells to reverse charge and damage them.

When I've opened up a battery pack,
I usually find one or 2 of the 10 cells is really low on voltage, the
others being on about 1.2volts.

They will be the cells you have damaged.

They need to be recharged at the first hint of falling voltage. They
also need to be charged correctly, rather than just left on an endless
trickle charge. An automatic cut-off charger is the best way.


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Bosch cordless drill battteries
 

Mike Harrison explained :
Anyone any suggestions for getting longer life out of NiCd drill batteries.
Mine always seem to expire after a couple of years or is this normal life?
I
only use the drill every couple of weeks for perhaps 10 minutes work and
only recharge when its completely flat. When I've opened up a battery pack,
I usually find one or 2 of the 10 cells is really low on voltage, the
others being on about 1.2volts.

Geoff.

If a cell reads zero volts, it has probably dendrited - whiskers of metal
form and short the cell.
These can often be recovered by passing a very brief, heavy current (10-30
amps for a C-size cell
for a second or 2 max) through it.

The safest way is to charge up a high value capacitor (from a car
battery or similar), then discharge it across the cell to blow them
away. If you feel braver (and perhaps more foolhardy), splashing the
contacts across a car battery also works if you are quick. Make sure it
is positive to positive.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Bosch cordless drill battteries
 

What on earth is "reverse charging"? I always understood that you were
supposed to completely flatten the battery before recharging and that you
shouldn't recharge a partially charged battery due to the "memory effect"
"Harry Bloomfield" wrote in message
...
Geoff Norfolk wrote :
Anyone any suggestions for getting longer life out of NiCd drill
batteries.
Mine always seem to expire after a couple of years or is this normal
life? I
only use the drill every couple of weeks for perhaps 10 minutes work and
only recharge when its completely flat.

Which will cause some cells to reverse charge and damage them.

When I've opened up a battery pack,
I usually find one or 2 of the 10 cells is really low on voltage, the
others being on about 1.2volts.

They will be the cells you have damaged.

They need to be recharged at the first hint of falling voltage. They
also need to be charged correctly, rather than just left on an endless
trickle charge. An automatic cut-off charger is the best way.


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Bosch cordless drill battteries
 

Geoff Norfolk brought next idea :
What on earth is "reverse charging"? I always understood that you were
supposed to completely flatten the battery before recharging and that you
shouldn't recharge a partially charged battery due to the "memory effect"

Some suggest that the memory effect is a myth, however....

Reverse charging is what happens when you have several cells in series
and you discharge them to the point that the weakest ones voltage first
falls to zero, then starts to become charged with the wrong polarity as
the stronger cells continue to discharge through that cell.

The charging process pushes the current through one way, during the
discharge the current flow is the opposite way. You can never get
perfectly balanced and equal capacity cells, therefore the one with
least capacity will become reversed charged if the discharge process
were to continue after the weak one had fully discharged itself.

So for best life, you should always put the battery pack on charge at
the first hint of the drill slowing down.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Bosch cordless drill battteries
 

In article , Geoff Norfolk
wrote:

What on earth is "reverse charging"?

What on earth are you referring to? As you posted upside down and failed to
trim, your response make little sense.

--
AJL